Numerosity discrimination: Both time and number matter.

Pigeons were trained on a psychophysical choice task to discriminate between 2 fixed ratios and tested with probe ratios intermediate to the training requirements. Absolute and relative ratio size were varied over conditions. In a final condition, Ss were transferred from the number-based discrimination to a time-based discrimination. The times taken to emit the ratios were recorded, and ratio value and ratio time were used to predict choice in a multiple regression analysis. Psychophysical analyses of the response number dimension suggested a scalar counting principle of numerosity discrimination, similar to that found with temporal dimensions. The multiple regression analysis indicated that both number and time contributed to the discrimination of ratio value. The results of the transfer test indicated individual differences in the degree to which responding was controlled by temporal vs numerical factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dimensions of stimulus complexity.

Animal reaming research has increasingly used complex stimuli that approximate natural objects, events, and locations, a trend that has accompanied a resurgence of interest in the role of cognitive factors in reaming. Accounts of complex stimulus control have focused mainly on cognitive mechanisms and largely ignored the contribution of stimulus information to perception and memory for complex events. It is argued here that research on animal reaming stands to benefit from a more detailed consideration of the stimulus and that James Gibson's stimulus-centered theory of perception serves as a useful framework for analyses of complex stimuli. Several issues in the field of animal reaming and cognition are considered from the Gibsonian perspective on stimuli, including the fundamental problem of defining the effective stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Paul Feyerabend und die Softwaretechnologie

Zusammenfassung   Der folgende Beitrag ist ein Pl?doyer für st?rkere methodische Standards in der Softwaretechnologie. Nicht immer werden wissenschaftstheoretischen Grunds?tze beachtet wie das Prinzip, da? Aussagen falsifizierbar sein sollten. Dies scheint die These der sog. Konstruktivisten zu best?tigen, da? n?mlich „objektive Wahrheiten“ in Wirklichkeit soziale Konstrukte seien. Der Beitrag pl?diert deshalb für eine st?rkere empirische Fundierung der Softwaretechnologie. Eingegangen in überarbeiteter Form am 07.09.1998     

Senile macular changes in the black African

One thousand black African and 380 white Caucasian patients over the age of 50 were examined for evidence of age-related macular changes, namely, drusen, pigment epithelial atrophy, and disciform macular degeneration. Drusen and pigment epithelial changes were found to occur twice as commonly in Caucasians as in Africans; there was a much greater difference in the prevalence of disciform macular degeneration between the 2 groups. The cause of the differences remains unexplained.     

Crowding and isolation: Determinants of agonistic and food-seeking behavior in Norway rats.

Alternately isolated and crowded 2 groups of 12 male Long-Evans rats. Order of housing and familiarity of the Ss with the test apparatus were also varied systematically. Ss were deprived of food, trained to bar press, and allowed to compete in pairs for sugar water in a Skinner box. Isolated pairs produced more agonistic and contact behaviors and fewer bar presses than did crowded pairs. Weight was found to increase more rapidly during free feeding when animals were isolated. Familiarity of only 1 isolate with the testing environment led to the display of less aggression than was observed in other isolate conditions. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bestimmung der Rückstände von aromatischen Dinitroverbindungen mittels gelchromatographischer Reinigung

European Food Research and Technology - Red pepper is a very important Hungarian spice which is widely used for seasoning food at home as well as abroad. During its production there is a...     

The attenuation of sound in gas—solid suspensions

Using mass, momentum and energy balances, a theory is developed which permits the calculation of the viscous and thermal attenuation of sonic waves in gas—solid suspensions. Equations are obtained giving the viscous and thermal attenuation coefficients as explicit functions of the solid particle diameter, the porosity, the gas viscosity, the specific heat of the solid material, the temperature of the suspension, the densities and heat conductivities of gas and solid, and the sound frequency. Experimental results agree well with the theory.     

Hybrid pattern recognition using Markov networks

Markov networks are inferred automatically for different classes of learning strings. In subsequent string-to-network alignments for test samples, the networks are used to deduce structural characteristics and to provide similarity measures. By processing the similarity measures as numerical-value features, standard nonparametric decision-theoretic pattern classifiers may be applied to determine class membership. The nearest-neighbor rule and linear discriminant-function classifiers are discussed, and their performances are compared with that of a maximum-likelihood classifier. The hybrid system's ability to determine string orientation correctly is investigated. Experiments with several thousand human banded chromosomes are reported     

Singular systems of partial difference equations

Sufficient conditions for the existence and uniqueness of solutions of singular systems of 2-D difference equations with constant coefficients are formulated. Linear transformation of the matrix coefficients leads to recursive forms of such systems of equations. The results are applied to standard 2-D state-space models of discrete systems and sufficient conditions of BIBO stability of these singular systems are obtained.